1. Field of the Invention
This invention relates to a torsional reed reference fluidic oscillator, and also to an improved torsional reed fluidic amplifier.
2. Description of the Prior Art
In a torsional reed reference fluidic oscillator, the frequency of oscillation is determined by the mechanical resonant frequency of an oscillating reed member, wherein the reed member is a component of a torsional amplifier of the oscillator. However, this reed member is normally a thin elongated planar structure which tends to have a flapping motion when it oscillates about an axis determined by a pair of torsional members positioned perpendicular to the major axis of the reed member. Since the square of the mechanical resonant frequency of the reed member is generally equal to the torsional spring rate of the torsional members divided by the moments of inertia of the mass of the reed about its torsional axis, this formula relationship would be expected to accurately predict the operating frequency of the oscillator. However, the flapping motion of the reed member imposes thereon another mode of oscillation which causes a shift in the desired center frequency of the oscillator, thereby limiting the stability and predetermined accuracy of the oscillator.
Similarly, this torsional reed reference fluidic oscillator has a tab extending from one end of the reed member perpendicular to the plane of the reed member and parallel to the major axis of the torsional members. The tab normally has a hole therethrough, and is received within channels of two separate plates. When the hole in the tab is aligned with the channel in one of the plates, that plate provides an output signal for the amplifier, and when the hole in the tab is aligned with the other of the plates, that other plate provides another output signal for the amplifier. These output signals are, in turn, coupled to fluidic feedback means for converting the output signal to first and second input signals which are applied to the reed member at a proper phase relationship for insuring operation of the entire apparatus as an oscillator. However, since the plane of the tab is parallel to the torsional axis of the reed member, supply fluid coupled to the channels of the plates impinges on the tab and applies a torsional force to the reed member. This torsional force again causes a shifting in the resonant frequency of oscillation of the reed member as it oscillates about its torsional axis, and and limits the stability and predetermined accuracy of the fluidic oscillator.
Furthermore, this torsional reed reference oscillator should be operated at a high pressure to insure that it would always be self starting. However, a high operating pressure generally causes a decrease in the overall performance of the oscillator, and can severely limit its predetermined accuracy and frequency stability. Still further, since the mechanical characteristics of the components of the oscillator often change over the desired operating temperature and pressure ranges, the frequency stability of the oscillator over this broad range is difficult to maintain.